It didn't really matter. As a small child, Idries had been weaker than the others, or so Prisoner Zero had been told. So what he lacked in strength he decided to make up for in guile, but his mind wasn't quite as fast as the others' either. That was why Hassan eventually gave him a knife.

The next boy to pick on Idries got his cheek opened in a single slash. There were two things Hassan told Idries to learn from that incident.

The first was that skin stretched tight over bone splits easily and bleeds more than seems possible. The second was that their uncle Caid Hammou was right. There are some things in life that need to be done only once. Almost everybody left Idries alone after that.

It was just after dawn and Prisoner Zero was already tired. He'd started early, partly because, these days, his dreams were even more complex than his life and sleep had become a tougher choice than polishing the walls; but mostly he'd started early because whole areas of the hall still needed to be soaped and until his tadelackt plaster was sealed it remained vulnerable to just about everything.

He knew that Idries found his ability to plaster both comic and disconcerting. People like him weren't supposed to acquire the skill. Such jobs were meant to be left to those who grew up with them. And the trick of working in tadelackt was something handed down from father to sons, a family secret retained by generations of plasterers in Marrakech, Fez and Rabat.

Yet all it really took was a smattering of basic chemistry. At least, that was all it took for Prisoner Zero.

Produced by burning limestone contaminated with clay, tadelackt was different. The silico-aluminates from the burning combined with water to produce a plaster which allowed for hydraulic setting. Although the real skill, not to mention the hard work, came when the finish needed polishing. This had to be done by hand, using the force of a flat pebble to control crystallization. As for the soap, that was required to seal the surface and impede chemical reactions, allowing a finish as hard and smooth as polished marble.

"What's going to happen?" Idries said.

"I'm going to finish polishing," said Prisoner Zero, "then start with the black soap..."

That wasn't what Idries meant and Prisoner Zero knew it. Hassan's rat-faced cousin was there because Caid Hammou had given him the job of babysitting Prisoner Zero.

It was typical of Hammou and Hassan to combine keeping their guest safe with making him work for his keep, a very North African combination of exploitation and obligation which Prisoner Zero still found strange after all these years.

There were twelve bedrooms in Hassan's new kasbah, four bathrooms, five reception rooms and a kitchen, built around a central courtyard with a fountain as yet unattached to any source of water, and Prisoner Zero got the feeling Hassan intended to have him plaster them all. Idries had not even seemed surprised that first morning to find Prisoner Zero alive when all the papers were busy reporting him dead.

He'd just turned up, as ordered, in a jeep laden with lime plaster and released Prisoner Zero from the chair to which he'd been tied. That was when Prisoner Zero first realized that being driven out to the half-built kasbah didn't necessarily equate with being shot.

"What are you smiling at?"

"Your boss."

Idries looked worried. "What about him? No, wait..." The rat-faced man held up one hand, common sense changing his mind. "Don't tell me. I don't want to know."

"You think he's going to kill me?"

"Caid Hammou?" As if Prisoner Zero might mean anyone else.

"Yeah, your uncle, the boss."

"No," said Idries. "If he was going to do that then you'd be dead."

"And this house would never get finished."

"There are other plasterers in Marrakech," Idries said flatly.

"Thousands of them," agreed Prisoner Zero. "So why doesn't Hassan get someone else? I've got other things on my mind."

Like ghosts and dreams and a nagging, insistent feeling that something kept looking at the world from behind his eyes and not liking a single thing it saw. A feeling which manifested itself as a low-level headache in the back of Prisoner Zero's skull where the darkness lurked.

"Hassan believed you were long since dead," said Idries. "We all did."

Prisoner Zero thought about his final months in Amsterdam, the squat overlooking the canal and the fire. "I was," he said. "Then I went to Paris."

Idries made a sign against the evil eye, his reaction so instinctive it operated below the level of conscious thought. "You shouldn't say such things."

"You weren't there," said Prisoner Zero.

"But you came back to Morocco."

"Yeah." Prisoner Zero smiled. "That's one way of putting it." Two days on a cheap coach, a ferry crossing from Alicante and a week of sleeping under flowering almond trees, walnuts and finally palms as he hitched south, doing his best to avoid anything that looked like authority. The heroin lasted from the real Paris to Paris sur la Mer, otherwise known as Casablanca, leaving him sick and sweating.

"And before..." Idries skirted around the incident in Djemaa el Fna, yet they both knew what he meant. "Hassan asked around. Apparently you were plastering an old brothel at the back of Maison Tiskiwine. For food..."

"For keep," said Prisoner Zero, "there's a difference."

"Ahh."

Prisoner Zero smiled and let Idries think he meant sex, though that wasn't it. He'd enjoyed seeing Leila's girls pass by in their thongs or camiknickers but he was there for anonymity, to be regarded like an old piece of furniture, comfortable and useful but consistently invisible. A woman in a souk had been talking about hiring a plasterer when the man who wasn't Jake had interrupted, offered his services.

"You've done the work before?"

"Of course."

"Where?" Leila's eyes were bright, openly suspicious.

He named Riad-al-Razor, near Bab Doukkala.

"Never heard of it."

"It was a while ago."

The rate Leila mentioned was so low that even Prisoner Zero had raised his eyebrows, only accepting when he realized she was about to turn back to her conversation.

"Look," Idries said. "You need to answer that."

"No," said Prisoner Zero. "I don't. So stop bothering me."

Idries began to shrug, looked at the man he was there to watch and smiled, understanding spreading slowly across his thin face. "You're not meant to answer it," he said. "It's a signal."

Prisoner Zero said nothing. He handed his polishing stone to Idries, climbed down from the ladder and walked slowly to the window, stopping while he was still in shadow.

Ghosts and the memories of things still to happen were waiting for him out there. And yet by next spring there would also be a garden of small palms and ornamental bushes, a fountain fed by water piped from higher up the valley. Pegs already marked where the beds were to be dug and foundations had been laid for a road to run from the gate to a parking area along one side of the kasbah.

Prisoner Zero tried to imagine what it would be like to own such a house and found he couldn't. It was years since he'd owned more than his memories and the clothes in which he stood. Even the flat in Paris was owned by a family trust, his tiny allowance for food, electricity and gas unchanged since the day it was first paid.

"I need some cigarettes," he said, turning back from the window.

"You don't smoke."

"How would you know?"

Idries sighed. "I'll get some tomorrow," he promised.

"Now," Prisoner Zero said. "I mean it. I can't finish this until I've got some." He indicated the area of wall he'd been polishing with the fist-sized lump of agate. It had a dull shine like poor quality marble.

"What kind?" Idries asked.